Part 1. The Field of the Invention
This invention relates to electrical energy power supplies and more precisely, to specialized batteries and processes for producing such batteries which have special utility in packs or assemblies comprising a container holding self-developing film unit(s) integrated with an electrical power supply system.
Part 2. Description of the Prior Art
U.S. Pat. Nos. 3,705,542; 3,543,662; 3,543,663; 3,595,661 and commonly owned, copending U.S. Patent Application Ser. No. 399,321 filed Sept. 21, 1973 by S. M. Bloom, J. W. Foley and N. S. Hadzekyriakides relate to photographic film packs comprising an enclosure containing self-developing film units integrated with a power supply system. Such film packs are presently employed exclusively in a photographic camera sold by Polaroid Corporation of Cambridge, Massachusetts, U.S.A. under the trade name "SX-70".
Essentially, film packs described in those patents and Application comprise an opaque enclosure containing a dark slide for covering an exposure station in a forward wall of the container, a stack of individual "self-developing" film units positioned behind the dark slide, means for urging the stack of film units towards the forward wall to position the uppermost film unit in the stack in the exposure station and an electrical power supply system for operating electrical mechanisms of a camera designed for using the pack.
When the film pack is inserted into the camera, the dark slide is removed through a withdrawal slot at one end of the enclosure to uncover the exposure station and the uppermost film unit is urged into position in the exposure station by the means mentioned before which usually involves a spring biased platen.
After exposure, the uppermost film unit is advanced, from the exposure station through the withdrawal slot into engagement with cylindrical rollers and processing of the exposed film unit is initiated as the unit is advanced between the rollers.
"Self-developing film" of such packs is sometimes described as an integral negative-positive film unit having as essential elements, a photosensitive element having a photosensitive system for providing a diffusion transfer image pattern, an image-receiving element, an opacification system and a rupturable container holding a processing composition. The elements are integrated with the unit so that the processing composition can be distributed within the unit to install a diffusion transfer image pattern in the image-receiving element and the pattern is viewable against a reflective background without separation. The film units are adapted for processing outside the camera since effective protection against further exposure is provided by way of the opacification system which in some integral negative-positive film units is integrated with the unit prior to exposure of the photosensitive system while in others, the opacification system is integrated with the unit after exposure. In the preferred integral negative-positive film units, the opacification system comprises a combination of light-absorbing dyes and a light-reflecting material or pigment and this combination is included in the rupturable container and distributed between the photosensitive and image-receiving elements after exposure. Further details relating to the integral negative-positive film units may be found in U.S. Pat. Nos. 3,415,644; 3,415,645; 3,415,646 and 3,647,437 among others.
As mentioned, the film packs of the present invention also include an electrical energy power souce contained within the enclosure. Essentially, the power source comprises a battery of the type described in detail in U.S. Pat. Nos. 3,543,662; 3,563,805; 3,617,387 and 3,734,780 among others. Such batteries are flat or planar primary batteries of the LeClanche type including a zinc anode system, a manganese dioxide cathode system and an aqueous ammonium chloride, zinc chloride and usually a small amount of mercuric chloride. When the film pack is inserted into the camera, the battery integrated therewith is connected to the camera's electrical system to provide the electrical energy sufficient to operate any circuits of the camera which can include an automatic exposure control circuit, a flash mode circuit, film transport circuits and processing mechanism circuit among others. The output of the battery is designed to continue to supply the requisite energy until all film units in the pack are exposed and transported from the camera. At that time, the pack--containing the integral battery--is discarded.
The desired performance characteristics of batteries of the type described above are well defined. Essentially, such batteries must be compact and specifically configured for effective integration and assembly with the film pack and at the same time provide the requisite electrical energy for efficient operation of the camera and related accessories until depletion of the supply of film units in the film pack. Additionally, the batteries are designed to be discarded together with the empty film pack. Accordingly, an economic constraint is involved requiring that the batteries be produced by way of high volume, low cost processes which inevitably dictates the involvement of a high speed, on-line continuous process capable of efficiently assembling batteries and providing maximum production of acceptable batteries with minimum rejects.
In the past, a high volume, low cost production process for batteries of the type described has involved assembly techniques utilizing wide, continuous and multi-zoned webs of sheet elements of the battery. These webs are selectively manipulated along an assembly line to simultaneously provide an interconnected plurality of individual battery assemblages which are finally cut into discrete batteries.
Battery assembly operations involving use of wide, multi-zone webs of sheet elements of the battery have met with some difficulties. For example, some of the sheet elements of the battery such as the electrode supports and intercell connectors are fabricated of webs comprising electrically conductive webs providing sheet element and electrochemically active materials involved in the battery assembly operation provide an electrically interconnected plurality of individual batteries which can result in back-up voltages being generated during assembly. Such back-up voltages can adversely affect battery performance unless specialized precautions are employed to minimize or compensate for the phenomenon. Also the requisite of cutting or shearing the interconnected plurality of individual battery assemblages into discrete batteries can increase product rejection because of edge shorting which can occur between contiguous electrically conductive sheet elements due to improper cutting or shearing.
An improved, high volume, low cost production process for producing batteries of the type to which the present invention pertains is disclosed in commonly owned U.S. Patent Application Ser. No. 478,106 filed concurrently with this application by the present inventor. Essentially, the process disclosed involves a battery assembly operation involving a continuous web of electrically insulative material which functions as a carrier on which the discrete components of each battery are assembled to provide a continuous web of individual non-electrically interconnected batteries. Because electrical interconnection between the individual battery assemblies does not exist, back-up voltages or the like are not obtained. Another advantage presented by the above-described process resides in the manner by which the individual batteries assembled on the carrier are cut into discrete batteries. The cutting operation involves cutting of the carrier without exposure of electrically conductive sheet elements of the battery to cutting or shearing thereby avoiding edge shorting possibilities.
The present invention is addressed to high volume, low cost battery assembly operations wherein discrete sheet elements and electrochemical components are employed in assembling of flat, planar, primary batteries of the type described before. Essentially, the present invention provides an improved, highly efficient assembly process for such batteries which permits maximum production of batteries providing the desired performance characteristics with minimal product rejection.